From: Steven Rostedt <rostedt@goodmis.org>
Date: Mon, 12 May 2008 19:21:00 +0000 (+0200)
Subject: lockdep: update lockdep_recursion on graph_lock
X-Git-Tag: v2.6.27-rc1~1102^2^2~1^2~51
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=bb065afb8ebd07a03155502dba29ebf0f6fe67e8;p=linux-2.6

lockdep: update lockdep_recursion on graph_lock

With the introduction of ftrace, it is possible to recurse into
the lockdep functions via the mcount call. To prevent possible
lockups, updating the lockdep_recursion counter on grabbing the internal
lockdep_lock should prevent deadlocks.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---

diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index 90a440cbd6..65548eff02 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -82,6 +82,8 @@ static int graph_lock(void)
 		__raw_spin_unlock(&lockdep_lock);
 		return 0;
 	}
+	/* prevent any recursions within lockdep from causing deadlocks */
+	current->lockdep_recursion++;
 	return 1;
 }
 
@@ -90,6 +92,7 @@ static inline int graph_unlock(void)
 	if (debug_locks && !__raw_spin_is_locked(&lockdep_lock))
 		return DEBUG_LOCKS_WARN_ON(1);
 
+	current->lockdep_recursion--;
 	__raw_spin_unlock(&lockdep_lock);
 	return 0;
 }